Abstract: A D.C. to A.C. inverter using switching transistors driving a multiple-core transformer which includes a high-permeability saturable core upon which both the primary and secondary windings are wound and one or more lower permeability non-saturating cores upon which the primary and/or secondary windings are wound to provide additional self-inductance. The inverter switching transistors drive the two halves of the transformer's center-tapped primary winding on alternate half-cycles under the control of a feedback winding which is wound on the saturable core. A non-saturating core about which the primary winding is wound, and a capacitor connected in parallel with both halves of the primary winding, protects the switching transistors against transients, prevents the saturating core from going into hard saturation, and efficiently transfers energy stored in the leakage inductance of the primary winding from half-cycle to half-cycle.

Abstract: A power supply including a high frequency inverter circuit coupled to an electron discharge lamp load through a special purpose transformer is disclosed. The transformer is wound on a saturable ferromagnetic core structure forming a first magnetic flux path coupling the primary and secondary windings of the transformer and a second shunt magnetic path including an air gap which carries and increasing share of flux as load current increases. The switching of the inverter circuit occurs in response to the partial saturation of the core. Auxilliary windings serially connected with the primary winding of the transformer and wound about the shunt magnetic path enhance the current regulating properties of the supply.

Abstract: A solid-state electronic ballast circuit for supplying direct-current power to an electric discharge vapor lamp is disclosed. The source-drain channel of a Vertical Metal Oxide Semiconductor (VMOS) Field Effect Transistor (FET) is connected in parallel with a fixed ballast resistor, the parallel combination being connected in series with the lamp across a DC source. A resistance network controls the conductivity of a bipolar transistor, which in turn controls the conductivity of the VMOS channel, in response to variations in both lamp voltage and current. The ballast circuit may be manufactured as a part of the lamp bulb assembly, the ballast resistor taking the form of an incandescent lamp filament mounted in the same outer bulb with the vapor lamp arc tube. A variable resistance may be employed to manually adjust the level of illumination delivered by the lamp, or a light-sensitive phototransistor may be employed to deliver constant illumination.

Abstract: A circuit for supplying controlled direct current power to an electric discharge vapor lamp during ignition, warm-up and normal operation. A bridge rectifier and a capacitor voltage doubler convert standard alternating current line voltage into a direct current voltage of adequate magnitude to operate the lamp. The lamp is connected in series with a semiconductor control circuit across the DC supply. The semiconductor control circuit operates as a resistive ballast whose effective resistance decreases as vapor pressure within the lamp increases during warm-up, thereby limiting lamp current to a safe value immediately after ignition while reducing the amount of power dissipated in the ballast circuit during normal operation for improved efficiency. In a second embodiment, the conductivity of the resistive ballast circuit is controlled in response to variations in both lamp voltage and lamp current to control the amount of power delivered to the lamp.